1. Field of the Invention
The invention relates to servovalves and refers more specifically to a two-stage miniature servovalve having an electromagnetic positioner, a jet pipe pilot stage, and a four-way hydraulic valve, main valve stage incorporating position follower spool control, which miniature servovalve exceeds ARP 490Csize IB requirements and allows passage of up to one hundred fifty micron particles without malfunction.
2. Description of the Prior Art
Prior servovalves have had difficulty in meeting performance, simplicity, stability, ruggedness and reliability requirements of aerospace related industries in a valve sufficiently small and light enough to be practical in many aerospace applications.
Prior servovalves have often included positioners which were mechanically, hydraulically or electrically actuated. Such valves have also often included spool or flapper type pilot stages. In addition, wherein the second stage or hydraulic valve portion of prior servovalves have been four-way hydraulic valves, they have often included metering spools having only three lands thereon whereby the critical dimensions of the valve spool are effectively elongated by varying hydraulic valve pressures.